Stencil film



June 4,1940. A, A, HATH 2,203,280

sTaNcIL FILM Filed sept. 5, 1939 r' i 1 E /1 i :l

l f5* j Illlllll l T6 f ,5

ZZ 4mm A. /mf/f 7 ATTORNEY f 4 sNvEN-rorz.

Patented June 4, 1940 l UNITED STATES Aiuvralvr ori-ICE Application A No. 293,355

This invention relates to the cutting of stencils stencil sheets upon which type is to be impressed,v of the type now commonly employed in duplicatseveral factors should be considered; for example, ing machines, or for forming photographic negathe film must be thin enough to transmit the tives. pressure to the stencil, and only over the area 6 The stencil sheet is formed of a very thin tissue Where the pressure is applied. This requirement 5 paper, commonly termed Japanese tissue or is met by stencil sheet films such as described in Yoshino. This paper is usually less than .001 of the prior patent referred to hereinbefore. Furan inch in thickness, andvis-quite fragile and thermore, the thinner the nlm the more accudelicate.- Over` one face of this is applied a waxy rately does the area impressed correspond to the 10 coating which may partially penetrate into the type or plate to be duplicated. 10 paper. Now in order to form a printing stencil, It has been found however that other conthe waxy layer is displaced at those places where sideratlons are quite necessary to obtain a sharp vthe printing ink or light is intended to penetrate and uniformly impressed stencil. These considthe stencil. This displacement is usually obtained erations involve the problem of ensuring against '15 by pressure exerted upon the tissue side of the applying unequal pressures upon the area of the 15 stencil sheet. It is desirable to exert the pressure stencil impressed by the printing type or plate; in such manner that the tissue of the stencil also. the ensuring that the face of the type or sheet is not punctured. The unpunctured tissue plate will not be worn unduly by the repeated can then act satisfactorily to distribute the ink contact and relative movement between the type in a uniform manner through the stencil, or to andthe film. It is accordingly another object 20 pass printing illumination therethrough. of this invention to provide a stencil sheet struc- In view of the inherent weakness of the tissue, ture such that will ensure against such undue and its lack of resistance to rupture, it has been wear of the type or plate, and at the same time, diilicult to ensure that the tissue stay intact, will ensure that the pressure transmitted to the and great care had to be exercised in the operasheet will be so uniform 'that the danger of 25 tion of exerting the cutting pressure. puncturing or otherwise injuring' the stencil is It is one of the objects of this inventionto greatly minimized. reduce the' degree of care required to prepare It is another object of this invention to provide' such stencils. a stencil protector film that also conveniently Ihe application of thepressure to the stencil serves as a typing guide. l 30 surface may be accomplished ,by manipulation This invention possesses many other advanof a stylus, which is especially adapted to freetages, and has Other Objects Which may be made hand Work. The pressure may also be applied more easily apparent from a consideration of by typewriter characters, operated as in typing, several embodiments of the invention. For this the stencil sheet being placed in the typewriter. purpose there are shown a few forms in the draw- 35. Or, a casttype plate or other printing plate ing accompanying and forming Dart 0f the presplaced in a press, may be used to impart the present specification. These forms, which illustrate sure upon the desired' areas of the stencil sheet. the general principles 0f the inVeniOn, Will 110W In order to protect the delicate stencil, supplebe described in detail; but it is to be understood mental sheets or lm of thin flexible material that this detailed description is not to be taken 40 40 have been used, interposed between the pressure in a limiting Sense, Since the SCOIJB 0f the i11- applying device (stylus, type, or printing plate) vention is best defined by the appended claims. and the stencil sheet. A form of lm for this Referring to the drawing: purpose is described and claimed inv Patent No. vFigure 1 is a planview, partly -broken away,

1,989,922, issued February 5, 1935, to A. A. Heath. of an embodiment of the invention; 45 Sheets of the character therein described are Fig. 2 is aside elevation thereof; quite satisfactory for stylus work; and with vor- Fig. 3 is a greatly enlarged fragmentary secdinary care, may also be quite effectively utilized tional view, illustrating the operation of the `for type or plate impressions. However, there is stencil film incorporating the invention, when some danger that the sharp edges of the type utilized in connection with typewriter type; 50

may cut through such a lm. Fig. 4 is a view similar to Fig. 3, illustrating It is therefore another object of this invention the use lof the stencil film in connection with to provide an improved protector film of this other forms of impression members, such as general character. i foundry type for the production of formagraph In the choice of a protecting 111m for use o stencils; and 65 when thefstencilis to'be used. Backingsheet fi,

sure sensitiy e adhesivejai'l the top edge; The top Ytri'may further be profor best results, may be made of a regenerated cellulose, gelatin, a resin lderivative, cellulose acetate or other material having resilience- It is Preferably approximately ve-thousanutnsfor, 15 an inch in thickness.

The protector film 5, to be deseribedfi'mrenn detail hereinafter, is shown in Ithis, instance,.as1 completely overlying thestencil is'lieet 'an'dinayf be attached to the backing sheet l, as by a pres:-

vid'ed-"with appropriate apertures by the aid of 'tmay be supported in a well known maniin ii a duplicating mach'ine-,and this top portion 4'e arranged tofbev retained on thestencil These may serve as guides;

WLspacing of the typed or printed matter on the stencil. The lines I5 define the width of the duplicatoi rand impose limits to the area to be utilized. At the top and bottom, lines I6 and il deiine a legal size space; and line I8 defines the lower edge of-a letter size space. The scale lines Il and I2 respectively at the top and bottom of the film, correspond to' typewriter character spaces, both pica and elite. Center line IS aids in centering laterally. Rectangles I3 and I may be marked to indicate post card sizes. Along each longitudinal edge, scale marks 2|, 2| corresponding to the spacingl of typewriter lines and spaces, may Ihe provided. All these guiding marks render it easy properly to space the matter to be imprinted on the stencil.

The film 5 is chosen to fulfill certain definite requirements. In view of the fact that the blank stencil sheets may lay in stock for long periods before use, the film E 'should resist any deterioration or changes due to temperature, humidity, or light conditions. Furthermore, it should be inert, so as not to react chemically with the stencil sheet, nor should it warp or become permanently distorted. This latter requirement is especially necessary where the protector film 5 is inscribed with guiding lines for typing or the like; for under such circumstances, material deviation from acl curacy of the spacings would be intolerable.

The film 5 should be so tenuousas to transmit accurately the pressure exerted upon its surface by an impressing member. The film for this purpose should be of the order of one one-thousandth of an inch (.001") thick. And, of course, the film should be at least partially resilient, and extensible.

The action of the film 5 as it transmits the pressure to the stencil i may'be best explained in connection with Figs. 3, 4 and 5. In Fig. 3 the reference numeral 1 indicates the impression face of typewriter type, shownin the pressure exerting position. In-this position, the wax coating 2 of the stencil has been displaced substantially entirely. 'I'he film 5 intimately contacts with the face 1 which may correspond to a line of a type such as the oval line forming an o. The film 5, being at least partially resilient, has considerable extensibility so that it can follow the impression formed by the type 8. It becomes thinner, due to the iiexing of the film over the pressure area of the type face l. The attenuation or thinning down, due to this stretch over face "i`ensures greater accuracy in forming the stencil. Furthermore, the film 5, after the pressure is removed,

is free jtoA return to lits normal, flat condition, `c ,fapableagain over tliesame area of accurately transmitting the. pressure to the stencil i, asV may be required for making corrections. For this pur- ,A pose, the film may readily be detached from backing i while the stencil is in the typewriter; landwaxycorrection material maybe applied to the Ystencil areato be retyped. The pressure "sensitive achesivjoinmg mm 5 to the backing t being greater than any elasticity thereof for the transmission of pressure to the stencil sheet I.4 t, y .'The material of the lm has inherently the prop- Y 55" 'I'he`f llmf5,wliich' is preferably transparentf'ior .'erty ofv malleability in that the material thereof ","tfranslucent, may carry printed marks defining A, 'ff 'margins and' spaces. for example to facilitate appropriate centering or undergoes a molecular-.distortion upon the application o f force applied thereto and vhas no pronounced tendency to restore itself to the original vdimension after the lremoval of the applied force.

medium, it equaliz'es the pressure-over the entire pressure area. This is of considerable importance as it minimizes very materially the danger of puncturing the delicate stencil sheet, and

also ensures that the resultant copies made by the aid of the stencil sheet will have uniform printing intensities.

Typewriter type such as illustrated by reference characterA 8 of Fig. 3 usually hasv sloping sides 9.

In a case of foundry type utilized in -formagraph stencil work, the type may have a form illustrated in Fig. 4. In this case the type I0 is shown as in pressure exerting position on the film 5, to form a pervious line upon the stencil sheet` I. Type of this character usually has abrupt faces.

Due to the tensile extensibility of the tenuous lm B, this ilm 5 does nthave any tendency to blunt the edges of the type. The film simply ows around the edges without material rubbing ef` fect.. Accordingly, the type stays sharp and clear for a long period.,

The inherent resilience of the film 5 thus provides a pressure transmitting'medium which has no abrasive or wearing effect upon the edges oi the type. In addition, as heretofore stated, the uent quality of the iilm 5 ensures a more uniformly distributed pressure over the area upon which the pressures are exerted.

Fig. 5 illustrates on an enlarged scale the impression of the letter H, through the film 5, onto the stencil sheet I. The areas are all clear and clean cut. v

There are a number of materials that can b used effectivelyfor the tenuous film 5,'and which fulll the important requirements outlined hereinbefore. v

Several types of materials fulfilling these'conditions vare nowpwell known. One of them is the material now on the market called "Plioform, which is a rubber derivativeand may be more ride, rubber hydrobromide `and rubber hydrocan be manufactured is set forth in Patent No.l

1,989,632 issued January 29, 1935, in the name of William C. Calvert; and also in Patent No. 2,139,647, issued in the name of the said individual on December 6, 1938. v

Of course it is not at all essential that the lm be a rubber derivative. Resinous compounds having equivalent properties may be utilized.

These resinous compounds in the form of vinyl derivatives having rubber-like qualities are now alsol well known. For example, a polymerized vinyl halide compound can be used, such for example as described in U. S. Patent 1,929,453, issued October 10,'1933, in the name of W. L. Semon. Vinyl derivative films are offered on the market under the name of "Vinylite or Koroseal.

The inherently advantageous properties of tensile resilience in extremely thin iilms utilizing materials of this character have been described in various publications. For example, in Industrial and Engineering Chemistry, vol. 26, page 123 of the issue of February, 1934, the vinyl and rubber derivative materialsare generally described, as well as their physical properties, in an article entitled Plioform-a new molding resin; chemical reactions of rubber and Plioform.

In the issue of June 1, 1933, of this technical magazine,.furthergdiscussions of the various uses of the vinyl resin are set forth.

While only a few of the possible forms of materials have been specifically mentioned herein, equivalent materials having similar properties may be utilized.

The backing sheet l, as heretofore described, is purposely made resilient so as to assist in the pressure equalization. This backing sheet may itself includeif desired a thin top layer of material 22 of the same general character as lm 5. 'I'his thin layer 22 may be adhered to the lower layer. This lower layer may be of comparatively thicker material, of cellulose acetate or the like, that has cushioning characteristics.

,What is claimed is:

1. In combination, a stencil sheet upon which pervious areas may be formed by application of pressure, and without perforating the sheet, and a tenuous iilm overlying said sheet having a large degree of permanent extensibility, said lm being made from material that serves as a fluent medium to transmit pressure to the sheet.

2. In combination, a stencil sheet upon which pervious areas may be formed by application of pressure, 'and without perforating the sheet, and a tenuous lm overlying said sheet having a large degree of permanent extensibility, said iilm being capable of substantial attenuation when urged into the stencil sheet by the application of pressure.

3. In combination, a stencil sheet upon which pervious areas may be formed by application of pressure, and without perforating the sheet, and a tenuous film overlying said sheet vhaving a large degree of permanent extensibility, said lm being made from material that tends to equalize pressure transmitted through the lm and exerted over the area to bel affected.

4. `In combination, a stencil sheet upon which pervious areas may be formed by application of pressure, and without perforating the sheet, and` a tenuous iilm overlying said sheet having a large degree of permanent extensibility, and capable of deformation upon application of pressure to be transmitted through the lm, to conform closely to the operating areas of the pressure exerting element.

5. In combination, a stencil sheet upon which pervious areas may be formed by application of pressure, and without perforating the sheet, and a tenuous lm -overlying said sheet having a large degree of permanent extensibility, said nlm being made from material that transmits pressure to the sheet not only in the direction of the force ap plying the pressure, but in other directions as well.

6. In combination, a stencil sheet upon which pervious areas may be formed by application of l pressure, and without perforating the sheet, and' a tenuous film overlying said sheet having a large degree of permanent extensibility, and lmade from a rubber derivative. t

7. In combination, a stencil sheet upon which pervious areas may be formed byapplication of pressure, and without perforating the sheet, and a tenuous film overlying said sheet having a large degree of permanent extensibility, and made from a composition chosen from the group consisting of rubber hydrochloride, rubber hydrobromide and rubber hydroiodide.

8. In combination, a stencil sheet upon which, pervious areas may be formed by application of pressure, and without perforating the sheet, and

a tenuous nlm overlying said sheet having a vlarge degree of permanent extensibility, and made from a partially saturated composition chosen from the group consisting of rubber hydrochloride, rubber hydrobromide and rubber hydroiodide.

9. In combination, a stencil sheet upon which pervious areas may be formed by application of pressure, and without perforating the sheet, and a tenuous film overlying said sheet having a large degree of permanent extensibility, and made from a rubber hydrochloride having from 28 to 30.5 percent of chlorine.

10. In combination, a stencil sheet upon which pervious areas may beformed by application of pressure, -and without perforating the sheet, and a tenuous iilm overlying said sheet having a large degree of permanent extensibility, and made from a composition chosen from the group consisting 0f rubber hydrochloride, rubber hydrobromide 'and rubber hydroiodide including a photochemca1 inhibitor.

11. In combination, a stencil sheet upon which pervious areas may be formed by application of pressure, and without perforating the sheet, and a tenuous film overlying said sheet having a large degree of permanent extensibility, said lm made from a rubber-like vinyl derivative. v

12. In combination, a stencil sheet upon which pervious areas may be formed by application of pressure, and without perforatingithe sheet, and a tenuous film overlying said sheet having a large degree of permanent extensibility, said lm having a thickness` approximating one thousandth of an inch.

13. In combination, a stencil sheet upon which pervious areas may be formed by application of pressure, and without perforating the sheet, and a tenuous lm overlying said sheet having. a large degree of permanent extensibility, said lm made from a rubber-like composition.

14. In combination, a stencil sheet upon which pervious areas may be formed by application of pressure, and without perforating the sheet, and a tenuous lm overlying said sheet having a large degree of permanent extensibility, said film made from a polymerized vinyl halide.

15. In combination, a stencil sheet upon which pervious areas may be formed by the application of pressure, and Without perforating the sheet, and a tenuous extensible lm overlying said sheet having a large'degree of permanent extensibility.

16. In combination, a stencil sheet upon which pervious areas may be formed by the application of pressure, and without perforating the sheet,

a tenuous lm overlying said sheet having a large degree of permanent extensibility, and a backing sheet below said stencil sheet and formed of extensible material.

1'7`. In combinatioma stencil sheet upon which pervious areas may be formed by the application of pressure, and without perforating the sheet, y

and a tenuouslm overlying said sheet'having a large degree of permanent extensibility, said illm A carrying guiding marks thereon, and made from material that resists permanent warping or distortion.

18. In combination, a stencil sheet upon which pervious areas may be formed by the application of pressure, and without perforating the sheet, a tenuous fllm overlying said sheet having a large degree of permanent extensibility, and a backing sheet below said stencil sheet and including a, 

